Electrical distribution networks are critical for the delivery of electricity to consumers and businesses from the transmission system. Such a network can include power lines, substations, transformers, and meters that are interconnected by thousands of miles of underground cables. Underground cable accessories, such as cable splices and disconnectable joints, are racked in underground structures to support and separate cable runs from each other. Typically, the cable accessories are installed on rack arms extending from the walls of the underground structure. These rack arms have various mounting positions which allows a splicer to make adjustments as new cable runs or other equipment are installed in the underground structure. Once a set of cable accessories are energized it can be time consuming and costly to de-energize the circuit for the purposes of re-positioning, because the process can interrupt electricity to residential and commercial areas until the procedure is complete.
Due to the critical need for the continual operation of electrical distribution networks, such problems have not been entirely ignored in the industry. Generally, a cable accessory rests on a fiberglass joint shield that is used to transport the energized or de-energized cable accessory. Cables are attached to the connectors of the cable accessory. Because of the restricted space in which cable accessories are normally installed, it can be difficult to use external equipment to lift, move, and/or reposition the fiberglass joint shield and cable accessory. Therefore, the process of moving the fiberglass joint shield and cable accessory is performed by wrapping nylon straps underneath the fiberglass joint shield. Thereafter, the nylon straps, fiberglass joint shield, and cable accessory are lifted using a crane or winch. However, there is a risk of the fiberglass joint shield sliding out of the lifting straps, because the nylon straps are not securely engaged to the fiberglass joint shield. This causes a serious safety concern, because the cables connected to the cable accessory can become partially disassembled due to an unsupported cable accessory and cause an electrical failure.
Yet another problem with the fiberglass joint shield used in the art is that it does not provide support for the cables attached to the connectors of the cable accessory. Shielded power cables are sensitive to bending. Therefore, extreme care must be taken in ensuring that the power cable is not bent around a small radius or sharp point, because it can lead to electrical failure of the power cable. The current fiberglass joint shield used in the art fails to address these concerns because it permits a portion of some power cables connected to the cable accessory to hang over a sharp edge. Therefore, the portion of the hanging cable can bend and result in electrical failure.
Another problem with the fiberglass joint shield used in the art is that it can easily bend, because it is composed of flexible material. This bending allows the lifting straps to slide out of position. In addition, the bending allows the sharp edges of the fiberglass joint shield to contact some of the cables connected to the cable connector, thereby resulting in an electrical failure.
Therefore, there is a need in the art for a joint shield with integrated mounting points. The integrated mounting points prevent the lifting straps from moving or becoming dislodged during the lifting and movement of the cable accessory.
There is also a need for a joint shield with raised sides and ends. The raises raised sides prevent a cable accessory from sliding off the front or back of the joint shield. Similarly, the raised ends prevent the cable accessory from sliding off the ends of the joint shield. In addition, the raised ends provide a support for at least a portion of some cables attached to the cable accessory.
Further, cable accessories, such as splices and disconnectable joints that are utilized in underground medium voltage applications, are typically covered in an arc proofing material. This material is arc and track resistant and is capable of withstanding exposure to plasma caused by an electrical failure without degrading as defined by industry standards. The arc proofing serves to protect the cable accessory from damage caused by other equipment failure, as well as containing a failure of the cable accessory itself. Currently, the connectors of the cable accessory are individually wrapped with arc proofing material, such as arc proofing tape or a molded boot made of arc proofing material.
A common problem with disconnectable joints is that the sleeve can become partially disassembled from the bus bar which can result in an electrical failure. In order to check for this condition, the arc proofing material must be removed for a splicer to visibly confirm that the sleeve is fully installed on the bus bar. Currently, this is accomplished by either cutting a window into the arc proofing tape or by removing the molded boot. Cutting the tape poses safety issues, because the splicer can inadvertently cut too deep and damage the sleeve or joint which could cause an electrical failure. Furthermore, removing the existing arc proof molded boot requires the use of substantial force, because the molded boot wraps underneath the connector of the cable accessory. The substantial force can cause excessive movement of the connectors of the cable connector, thereby resulting in an electrical failure.
Another apparent need in the art is for a removable arc proof cover that couples to the joint shield. The removable arc proof cover surrounds the cable accessory and is configured to allow a visual inspection of the cables connected to the cable accessory. The arc proof cover can also protect the cable accessory from external electrical failure, and contain the electrical failure of the cable accessory within it.
Further, there is a need in the art for a mounting point to secure an arc proof cover to the joint shield.
The art also does not exhibit a grasping point on the joint shield. The grasping point allows the splicer to grip the joint shield with their hand to assist with lifting and sliding the joint shield and its corresponding cable accessory.
There also exists a need in the art for a rigid support structure underneath the joint shield. The rigid support structure is configured to minimize the bending of the flexible joint shield.